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AP EAMCET · PHYSICS · Work Power Energy

A block of mass ' \(\mathrm{m}\) ' and charge ' \(\mathrm{q}\) ' is connected to a point ' \(O\) ' with an inextensible string. This system is on a horizontal table. An electric field (E) is applied perpendicular to the string and in the plane of the horizontal table. The tension in the string when it becomes parallel to the electric field is

  1. A \(\mathrm{qE}\)
  2. B \(2 \mathrm{qE}\)
  3. C \(\frac{3 \mathrm{qE}}{4}\)
  4. D \(3 \mathrm{qE}\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(3 \mathrm{qE}\)

Step-by-step Solution

Detailed explanation

Let the length of the string is L Using the work energy theorem \(F \cdot L=\frac{1}{2} m v^2-0\) \(q E \cdot L=\frac{1}{2} m v^2 \Rightarrow v^2=\frac{2 q E L}{m}\) If \(\mathrm{T}\) is the tension in the string. When it becomes parallel to the electric field.…